Hidden Galaxies Baffle Scientists

In the ongoing search for substance, scientists and astronomers have been running against a wall.

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The theory is as follows: everything in the universe is built from the bottom up; tiny particles attract larger ones until you have a solar system. Dark matter is widely regarded as outer space’s essential building block. It attracts the dust and gas that form stars and eventually galaxies, including ours, the Milky Way.

Based on what we know, scientists have built galactic simulations that predict how many galaxies are out there and confirmed those simulations with intense study of the stars. The only problem is the numbers haven’t matched up.

There are significantly more galaxies in the simulation than can be observed through telescope and this has driven scientists to ask why?

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The answer has finally revealed itself.

A study published this month in the journal Nature found a “cataract in the gravitational lens” to be one of many “dark galaxies”.

The Milky Way, M31 (Andromeda Galaxy), and many other observed galaxies have satellite galaxies surrounding them. Some of these are relatively large and bright (like the Large and Small Magellanic Clouds), but many are very faint and relatively low mass, such as the Sagittarius dwarf elliptical galaxy. Standard dark matter models predict large numbers of these dwarf satellites, far more than we’ve actually observed.

Mass affects the path of light, as a consequence of the general theory of relativity. For a sufficiently large mass, the light’s shift may be sufficiently large that we can measure it, and it can produce lensed images of the original light source. In gravitational lensing, the lens is a galaxy or galaxy cluster lying between Earth and a distant source, itself typically a galaxy. If the lens is directly in the line of sight, the image of the source galaxy can be distorted into an Einstein ring, a circular image of the source. By studying the shape and other characteristics of the image, observers can reconstruct details about both the lens and the source galaxies.

Dark Galaxies are not a new discovery. In fact, the first recorded discovery of a dark galaxy was in 2005. Until that point, astronomers, professors and geniuses who have long since earned a physics degree were baffled at the mystery of the dark galaxies, and why projections were not matching up with observations.

The discovery should come as a relief to astrophysicists developing theories of how galaxies form. “If there are no dark galaxies in the universe, then we must be missing an important piece of physics,” says Michael Merrifield at the University of Nottingham, UK.

Reports indicate that a team of astronomers has detected another distant dwarf galaxy. This undiscovered galaxy some 10 billion light-years away has the characteristic enormous elliptical shape of other galaxies that were discovered last year.

Dwarf galaxies have been on the to-do list of many astronomers for some time. These ancient lumps of star that are thought to have merged during the formation of the universe have long been thought to be around, orbiting other astronomical bodies and larger galaxies. However, very few of them have come close to being detected on telescopes to substantiate this theory.

As dark galaxies come to light, a clearer picture of the universe and the forces that govern it come into view.